Presentation on theme: "ASARECA Workshop; August 21, 2013"— Presentation transcript:
1ASARECA Workshop; August 21, 2013 Tackling the MLN Challenge through R4D – Initiatives by CIMMYT and PartnersBM PrasannaDirector, Global Maize ProgramCIMMYT, Nairobi, Kenya
2Emergence of MLN in eastern Africa September 2011: Disease first reported in the lower parts of Longisa division of Bomet District of Kenya.February 2012: Noticed in Bomet Central division, spreading into neighboring Chepalungu, Narok North, Narok South and Naivasha Districts of Kenya.April 2012: Disease further spread to Sotik,, Koinon, Transmara, Rumuruti, Kisii, Bureti, Kericho, Mathira East, Imenti South and Embu Districts of KenyaIn Tanzania: Lake zone (Mwanza and Musoma), Manyara, Arusha and Moshi
4Disease Symptoms Poor seed set and shrivelled ears Shortened InternodesEarly leaf necrosis
5Pathogen DiagnosisCollaboration between KARI, CIMMYT and USDA/OSU (Wangai et al. 2012)First report of MCMV in Kenya.MLN is a viral disease caused by combined infection of maize with Maize Chlorotic Mottle Virus (MCMV) and any of the Potyviruses infecting cereals (e.g., SCMV, MDMV or WSMV).
7Global occurrence of MCMV/MLN CountryMCMV / MLNYearReferencePeruMLN1973Castillo and Hebertt (1974)USACLN1976Niblett and Cafflin (1976)Argentina1982Teyssandier et al. (1982)MexicoMCMV/MLN1987Delgadillo and Gaytan (1987)ThailandMCMV1983Cited in Uyemoto (1983)BrazilChina2011Xie et al. (2011)Kenya2012Wangai et al. (2012)TanzaniaCIMMYT Task Force Report to Ministry of Agriculture, TanzaniaUgandaGodfrey Asea’s presentation in MLN Workshop (Nairobi; Feb 12-13, 2013)Rwanda2013Claver Ngabiyasonga’s presentation during MLN Training Workshop (Nairobi; July 1, 2013)
8MLN in a Hybrid Seed Production Field in Tanzania
9Seed industry under stress in EA Seed demand has decreased in the MLN-affected region by several thousand tons.Demand has changed; sales have reduced.Lots of carry over seed.Import restrictionsSeed treatment with systemic insecticides:Increase in cost of seedProduct not availableSevere vulnerability of commercial varieties released in KenyaScreening of 119 commercial maize varieties (both hybrids and OPVs) released in Kenya under MLN artificial inoculation trials in Naivasha and Narok in Kenya revealed 117 if these are highly vulnerable to MLN!Source: STAK-KARI trials ( )
10Why is MLN devastating in EA? MCMV is new to the region + interaction with SCMV (new strains?) in the regionConducive environment for survival and spread of insect vectorsContinuous maize cropping in certain regions – build-up of virus inoculumWidespread cultivation of susceptible germplasm that has never been screened for MCMV
12MLN Regional Workshop and Field Day (Feb 12-14, 2013) 70 scientists, seed company breeders/managers, and representatives of Ministries of Agriculture and regulatory authorities in Kenya, Uganda and TanzaniaTraining on MLN disease diagnosticsMLN field day showed responses of diverse maize germplasm to responses to MLN under high disease pressureKEPHIS representative announced the commitment to fast-track MLN resistant hybrid release.
13Optimizing artificial inoculation protocols SCMV amplificationMCMV+SCMV amplificationInoculum preparationMCMV amplificationInoculum application using a mounted pressure sprayerin a trial in Narok (MLN Hot Spot) in KenyaTechnical support from USDA/OSU and KARI
14Do we have elite maize germplam resistant to MLN? Screening of inbred lines developed by CIMMYT, IITA and KARI, as well as CIMMYT pre-release hybrids against MLN duringCIMMYT-KARI team evaluated so far ~1000 maize genotypes in MLN trials:335 elite inbred lines and 366 pre-commercial hybrids under artificial inoculation in Narok (Kenya)350 elite inbred lines and 135 pre-commercial hybrids under natural disease pressure in Naivasha (Kenya)10-15% of the evaluated maize germplam revealed resistance or moderate resistance against MLN!
15Promising CIMMYT inbreds and pre-release hybrids against MLN identified MLN-resistant lineMLN-susceptible lineMLN-resistant lineMLN-susceptible lineMLN-resistant line
17Several more promising pre-release hybrids under validation trials in Narok this season. Seed requests for promising inbred lines and hybrids will be attended to in July-August 2013.
18Ensuring a continuous flow of MLN resistant elite maize germplasm in SSA Integrating MLN resistance as an integral component of maize breeding strategy and product pipeline, across projects.Establishing a centralized MLN screening facility in KARI- Naivasha (under artificial inoculation) is in progressOpportunity for screening elite germplasm for CIMMYT, KARI as well as other public and private sector partners in eastern Africa.A network of MLN testing sites (under natural disease pressure) in eastern Africa to evaluate promising materials from artificial inoculation trials.
19CIMMYT‘s ongoing efforts in identifying/ developing MLN resistant maize germplasm Hybrids currently in NPT in different countriesPre commercial hybrids from different projectsElite SC widely used in ESAEarly and medium kits regional trialsElite inbred lines from different CIMMYT projectsDTMA and IMAS association mapping panelsSelected bi-parental mapping populationsCommercial hybrids from different companiesSelected landrace accessions from CIMMYT Gene Bank
20Accelerating MLN resistant germplasm development Molecular marker-assisted breedingPossible to identify major genomic regions influencing resistance to MLNCIMMYT-KARI team is presently undertaking GWAS and validation using biparental populations to identify molecular markers for MLN resistanceMolecular marker-assisted backcrossing for conversion of selected elite but MLN-susceptible inbred lines into resistant versions.MABC, if some major QTL can be found, reduces time required several-fold (2-3 BCs instead of 6-7 BCs).
21Preliminary QTL for MLN resistance (bi-parental popn) To be genotyped with GBSR % % & 5.4% % %Source CML CZL03014/CML444 CZL03014 CZL03014Shaded regions indicate the confidence interval of the QTL
23Accelerating MLN resistant germplasm development Using doubled haploid (DH) technologyA state-of-the-art maize DH facility is being established by CIMMYT in Kiboko Station; will be ready by Sept 2013.The DH technology, in combination with molecular markers, can help reduce by half the time taken for developing MLN resistant versions of existing elite susceptible lines.
24Seed Systems SupportInformation on elite inbreds and pre-release hybrids with resistance (R) or moderate resistance (MR) to MLN under artificial inoculation conditions (besides natural disease pressure) shared with public and private partners in ESA, including Kenya, Tanzania, Uganda, Rwanda, Ethopioa, Zimbabwe, Zambia, Mozambique, Malawi and South Africa.Seed requests received from several partners – seed exchange will take place in July-August, with first priority to institutions in eastern Africa.Some promising hybrids in NPTs and some more in pipeline – emphasis on wider reach through non- exclusivity, till supply is more than the demand.
25How can we better control MLN? Short-term Harmonizing maize plantings, and ensuring a maize-free periodPromoting good agricultural practices, including crop rotation with non-cereals (e.g., legumes)A massive awareness drive, including farmers and extension agencies -> for effective local quarantineSeed companies/ seed units to ensure that seeds are treated with appropriate seed dressers at the recommended rates.Guidance to farmers on regime of MLN management, including pesticide application in the field+ identification, fast-track release delivery of MLN resistant maize varieties
26MLN Epidemiology: Unanswered Questions Is MLN in eastern Africa only due to MCMV + SCMV or due to MCMV + any other member of Potyviridae in different countries?What alternate hosts of MLN-causing viruses are prevalent in the region? How best to control them?What are the primary or most active insect-vectors spreading the disease?How frequent is seed transmission of viruses, especially MCMV? When is seed transmission most likely to happen?Nelson et al. 2011
27Understanding MLN Insect-vector Dynamics Survey and identification of vectors endemic to eastern Africa that are capable of transmitting MLN-causing viruses, especially MCMV and SCMVDetermining patterns of insect-vector movement and MLN disease development under natural conditions.Understanding of the effects of novel seed treatment technologies on the biology of insect-vectors transmitting MLN-causing viruses, and virus transmission competence.A competitive grant call has been announced recently under the MAIZE CRP.AphidsThripsLeaf hoppers
28MLN-free Germplasm Exchange We can possibly exchange seed produced from a MLN- free location (e.g., Kiboko) in a MLN-endemic country (e.g., Kenya) to other MLN-endemic countries in eastern Africa (e.g., Tanzania and Uganda), but NOT to any country where MLN has not been reported so far, including Ethiopia and southern African countries.Seed for international shipment from an MLN-endemic country can only be produced in a MLN-free location, and following due diligence.MLN Quarantine Site to be established very soon in CIMMYT-Zimbabwe.Comprehensive protocols being developed by CIMMYT for rigorous compliance in ESA.
29AcknowledgementCIMMYT colleagues (Dan Makumbi, Yoseph Beyene, Bish Das, George Mahuku, Dan Jeffers, Mosisa Worku, James Gethi, Kassa Semagn, Mike Olsen, Stephen Mugo, Mike Listman, Florence Sipalla, Wandera Ojanji)KARI colleagues (Dr Mukisira, Anne Wangai and her team)NARS and seed company partners across eastern and southern AfricaUSDA/OSU (Peg Redinbaugh and her team)Donor agencies: Bill & Melinda Gates Foundation, USAID and SFSA
30The pessimist complains about the wind. The optimist expects it to change.The realist adjusts the sails.- William A. Ward